This disclosure is based upon, and claims priority from, French Patent Application Nos. 97/12444 and 97/14582, filed Sep. 26, 1997 and Nov. 14, 1997, respectively, the contents of which are incorporated herein by reference.
The present invention concerns the field of electronic chip devices comprising a communication interface, and their manufacturing process. It concerns in particular chip devices, the interface of which is by contact and/or antenna, such as chip card or label micromodule. It relates particularly to antenna devices which are disposable or used only once which can communicate over distances of more than 50 cm, especially at frequencies of several mega-herz to several giga-hertz.
International Patent Application WO 97/26621 describes a chip and antenna module which can be scanned as a label. Cards are produced by inserting the antenna module in a cavity of a card body and certain labels are produced by packaging the antenna module in some kind of support such as a tally, for example.
These modules comprise an interface support film, commonly called a printed circuit, which contains at least one interface under the form of an antenna and/or under the form of connection pads, a microcircuit such as a chip connected to the interface and an encapsulating material to protect the microcircuit and its connections. The antenna is placed on one face of the micromodule especially on the reverse side of the latter, while the other face can possibly be equipped with connection pads.
The interface support film should possess certain mechanical properties due especially to the requirements of modern production processes. In particular, it is so flexible that it can be rolled up on reels but equally rigid so that it can be transported by sprockets engaging the side perforations. The rigidity of the interface support film is also such that it will break if folded.
The support films presently in use are selected from among epoxy glass, polyimide, and polyethylene terephtalate (PET). They have the following typical properties and characteristics: a thickness of between 75 xcexcm and 125 xcexcm, elongation at break of less than 75%, temperature resistance up to at least 160xc2x0 C.
The interface itself is generally copper; it presents a hard surface, the tracks are in general narrow (50 to 200 xcexcm) and have precise definition in the order of a few microns. The interface in general undergoes surface treatment for example of the Nixe2x80x94Au type which makes it even harder, easier to weld and protects it from oxidation.
The devices produced according to the above requirements have the disadvantage of being too bulky for the use envisaged in the invention. In addition, they have limited applications which do not correspond to the aims of the invention listed below.
The main object of the invention is to design an electronic chip device with or without contact, powered or otherwise, which is very economic and nevertheless very reliable, and is compatible with a manufacturing process comprising the least number of operations and using the most economic standard techniques possible in such a way as to promote its use and make it disposable if required.
Another object is to design a device of the above type which can also communicate preferably beyond 50 cm (non-powered) and beyond a meter (powered).
Another object is to design and economically manufacture an antenna and/or contact module which can easily and directly be printed especially by the user.
Another object is to design a device of the above type which can be used with all reliability in a variety of conditions and on multiple supports.
Another object is to design and economically manufacture chip cards or tickets with or without contact.
Some of these objects are achieved by using an interface support film having properties totally distinct and opposite to those required for interface support films in the field of the chip cards presented above, but also by adopting a manufacturing process in a roll, then by adapting this process, especially in regard to the connection of the chip, to take into account the new properties of the film. Other objects are achieved by specific configuration of the device described below.
For this purpose the invention firstly is intended as an electronic chip device, comprising an interface support film having a support film and at least one flat conductive interface placed on the support film as well as a microcircuit connected to the interface. It is distinguished in that the interface support film possesses such properties that it can be creased or folded on itself without deterioration.
Good results have been obtained with a support film and an interface which can be creased or folded together according to a curve radius of less than 2.5 mm and preferably less than 1 mm.
This definition corresponds to the choice of a support film, the properties of which are intrinsically downgraded in comparison to state of the art support films and/or the reduced thickness combined with an interface, the intrinsic properties of which are equally downgraded in comparison to state of the art interfaces or those of reduced thickness. According to the invention, the properties of each (support film and/or interface (s)) should be considered in combination. They can in particular be enormously downgraded for both, or those of one very much downgraded and those of the other less so; the thickness of each can also be reduced to a greater or lesser extent according to the degree of downgrading of the support film and interface materials.
Due to such an association and combination, a reliable, low-cost device is provided in spite of the handling which it can be made to undergo.
It is to be noted that in certain cases the downgrading, for example in regard to rigidity, can be accompanied by other qualities in the final product, for example in regard to elasticity but which cause manufacturing difficulties. The downgrading should be understood in the context of the invention in relation to the properties presently sought in the field of chip cards.
According to one characteristic, the support film possesses a thickness of less than 75 xcexcm, the best results being obtained with a thickness of between 10 xcexcm and 30 xcexcm.
With such a thin support film the invention provides not only a saving in material with a potential bearing on the price and especially a saving in the weight of the final device, thus providing new opportunities of application described below.
According to other characteristics of the invention the support film can be preferably a polymer with an elongation at break of more than 80%, and/or Shore hardness of less than 80 and/or a vitreous transition temperature Tg of less than 0xc2x0 C. and/or a fusion temperature of less than 130xc2x0 C.
Preferably the support film is selected from among polypropylene (PP), polyethylene (PE), polyethylene teraphtalate (PET). In other cases it can contain fibrous material, for example cellulose or textile.
The metal of the interface is preferably natural with no surface treatment aimed at hardening it, for example the Nixe2x80x94Au type. Preferably it is less than 50 xcexcm in thickness. Aluminum and its alloys are the preferred metal.
Materials such as PE, PP and PET are very economically advantageous since they are produced in very long and wide rolls in a field distinct from chipcards, such as packaging. The PE/aluminum or PP/aluminum combinations the use of which the invention proposes as a base to create an interface support film, are equally very common, especially in the field of food packaging (for yogurt lids, champagne corks, etc.)
According to another characteristic, the device comprises a microcircuit preferably situated outside the turns, especially in a corner of the support film. Preferably again the microcircuit is placed directly on the support film.
Preferably the device also comprises an interface element known as xe2x80x9cstrapxe2x80x9d on the other face to pull back at least one end of the antenna in the vicinity of the chip.
Thus it is possible to keep free the largest printing surface possible and create a very thin device with a view to the applications detailed below, the chip being in contact with the support film. The use of the xe2x80x9cstrapxe2x80x9d is an interesting solution explained in detail below.
According to one extra characteristic and/or another aspect and method to implement the invention, the device is distinguished in that it comprises a compensation film placed on a support film, the compensation film having a recess containing the microcircuit and its connections.
The recess can contain a material to encapsulate the microcircuit and its connections. The encapsulating material is preferably contained at least in part by the walls of the recess.
The compensation film can be used in relation with any other existing support film of the earlier type but it is more interesting to use it in relation with an interface support film which can be folded in line with the invention.
The compensation film also has advantages when manufacturing the device, that of compensating for the height of the microcircuit and of protecting it, especially to enable printing over the entire surface of the device without damaging the microcircuit.
Its function is to level out the surface of the device in such a way as to create a device without projection and to receive, if necessary, another decorative and/or adhesive layer over the microcircuit.
It also protects the microcircuit from the compression which is exerted on it when it is fixed on any kind of support by an adhesive applied especially on the compensation film.
It also allows the low mechanical strength of the interface support film to be compensated, in particular during its various uses.
It can be selected from among the most varied materials and adapted to any use, without in any way changing the process described below.
The present invention is also aimed at chip tickets and cards containing the device. Preferably they comprise a card or ticket body made up by the compensation film. This means that they have a recess which contains the microcircuit, the compensation film, the support film and the interface extending outside the recess over the surface of the compensation film.
Thus economic chip cards and tickets with protection of the microcircuit, if required, are obtained.
According to an alternative version, the recess is a non through-penetrating cavity or one enclosed by an additional film.
The present invention is also aimed at a process for manufacturing an electronic chip device comprising an interface support film having a support film and at least one flat interface as well as a microcircuit connected to the interface, the process comprising operations according to which at least one interface support film is provided and connected to the interface. This process is distinguished in that an interface support film is provided possessing properties such that it can be creased or folded on itself without deterioration.
The invention is preferably implemented according to the economic method of engraving printed or lithographed designs on one or several of the conductive surfaces, previously combined with the support film.
Due to the choice of this support film and interface but equally due to the choice of the manufacturing method of the interface, a low-cost interface support film is produced, thus contributing a reduction in the overall price of the device.
The process is also distinguished according to an extra characteristic and/or another aspect and method of implementing the invention in that it comprises an operation according to which a compensation film is fixed on the interface support film, the compensation film having at least one recess suitable as a place for a microcircuit.
This operation can be used in relation with any other existing support film of the earlier type but it is particularly interesting to use it in relation with an interface support film which can be folded in line with the invention.
The compensation film reinforces the interface support film which thus risks being more mechanically resistant during the stages of the process, in particular in the course of transport by traction.
It equally enables the support film to be coiled up flat between each stage, if necessary, or for delivery to the customer. It thus cuts out the wasted use of an interlayer film presently acting as protection between the different manufacturing stages.
Printing can be carried out on both sides of the device without damaging the microcircuit.
If the microcircuit and its connections are encapsulated, the recess of the compensation film can have a containing function. The compensation film can serve if necessary to receive side perforations for transporting and positioning sprockets and will facilitate coiling on reels with the use of present means of transport.
The compensation film enables the device to be made from various materials. It can especially be based on cellulose or any polymer, fabric or any other material in film form.
According to another method of implementing the invention without compensation film, the interface support film is supplied as rolled strip and means of transport controlled by the tension of the support film are used for feeding it to at least one work station corresponding to the stages of the process, especially the transfer of the microcircuit and/or its possible encapsulation.
Due to this arrangement it is possible to convey an interface support film that is ultra-supple and elastic without damaging it, without resorting to a compensation film, without side transporting perforation being necessary and without disturbing its positioning and/or indexation before the various work stations of the process.
According to another characteristic the microcircuit is connected by ultrasonic welding of conductor wires. More particularly, it is possible to resort to welding by aluminum wire for aluminum pads or interfaces.
Resorting to this method of connection is particularly advantageous since it is reliable, standard and economic. As explained below, this method creates difficulties which would not recommend it for use on an interface support film having properties conforming to the invention.
According to another characteristic an interface support film having interface elements on both faces is used. In particular it is possible to fit a capacitor plate on each side and/or xe2x80x9cstrapsxe2x80x9d at the same time as the interface.
Thus it is possible to reduce the manufacturing cost of these interface elements since they can be manufactured at the same time with the same technology indicated above. A less economic alternative would consist of making a bridge connection above the turns in a specific operation or the addition of a discrete capacitor.
According to another characteristic the interface elements on each side of the support film can be connected through the support film by mechanical tears and mechanical contacts. If necessary it is possible to make these connections by ultrasonic methods.
The choice of thin interface support film and the choice of materials conforming to the invention make it possible to use such a connection process. It is particularly advantageous and economic as no additional materials are needed and it can be done in one operation which can be concealed in the manufacturing process of the device.